1. Field of the Invention
The present invention generally relates to connecting rods and, more particularly, to sintered metal connecting rods and methods of manufacturing sintered metal connecting rods.
2. Description of Related Art
One-piece sintered metal connecting rods generally have a large bearing end and a small bearing end. The small bearing end is intended for connection to the piston via the wrist pin and the large bearing end is designed to be connected to the crankshaft. Due to manufacturing and assembly considerations, the small bearing end may remain in one piece, and have a bearing and wrist pin slidably inserted therethrough. However, the large-bearing end must be separated or cut into two pieces in order to permit assembly of the large bearing end around the crankshaft.
Therefore, an end or cap portion at the large bearing end is fractured or broken away from a body portion of the connecting rod to permit subsequent assembly of the connecting rod onto the crankshaft. U.S. Pat Nos. 5,109,605 and 4,993,134, the disclosures of which are expressly incorporated herein by reference in their entireties, are exemplary of such connecting rods, the conventional method of separating the cap from the body, and the conventional cap alignment and attachment procedure.
As shown by these patents, there are known methods of separating the large bearing end along a separating or cracking plane into a cap and a body. The separating plane is defined by grooves that are formed in the large bearing end at the desired separation location. Cracking or separating the cap from the body results in a rough separating surface that can be matingly reattached with considerable precision. The cap and adjacent body portion include shoulders having aligned threaded bores. The cap is adapted to be threadably and compressibly secured to the body so as to cooperate with the body to define a bearing housing that surrounds the crankshaft and receives a pair of half-shell bearing sleeves.
To secure the half-shell bearing sleeves within the bearing housing, the above-referenced patents teach separating the cap from the body, and then machining radial locking-notches in the cap and body on either side of the separating plane. Following assembly, projections or tangs from the half-shell bearing sleeves radially project into the locking notches. The locking notches are oriented transverse to the grooves used to define the separating plane.
Despite the improvements made in the field of connecting rods and, more particularly, fractured sintered-metal type connecting rods, there exists a need for improvement. For example, these connecting rods suffer from the disadvantage that there is no reliable and economical means to prevent the bearing sleeves on the large bearing end from rotating. Apart from the method taught by the above-referenced patents, two methods are currently used. The first relies upon a frictional interference fit that is created when the bearing sleeves are compressed into the bearing housing. The second relies upon the half-shell bearing sleeves providing tabs or other projections that are pressed into a mating or accommodating structure on the face of the bearing housing. This process, which occurs at the end of manufacture, has been found to be unsatisfactory.
Therefore, there exists a need in the art for an improved method of connecting rod assembly wherein the large end bearing is reliably and securely fastened to the connecting rod. There further exists a need in the art for a connecting rod having a large bearing end that is adapted for separation of the cap therefrom, and that is configured to securely receive the bearing sleeve therein. There further exists a need in the art for a bearing sleeve assembly process that will reduce machining steps and manufacturing costs.
The present invention is directed toward a connecting rod and method of connecting rod assembly that removes or eliminates the disadvantages in the art. The present invention is further directed toward a simplified connecting rod and bearing assembly method that reduces machining and assembly costs.
In accordance with the present invention, a method for manufacture and assembly of a connecting rod includes the steps of casting a connecting rod, cutting a pair of grooves in a large bearing end of the connecting rod to define a separation plane, separating the large bearing end about the separation plane to define a cap member and a body member, inserting a first bearing member in the cap member and a second bearing member in the body member, and securing the cap member to the body member such that free ends of the bearing members are compressed and deformed to form at least one protrusion that extends into one of the pair of grooves and secures the bearing members against rotation relative to the large bearing end of the connecting rod.
In further accordance with the present invention, the pair of grooves are generally V-shaped and defined by a first surface provided by the cap member and a second surface provided by the body member. The protrusion engages one of the first and second surfaces.
In accordance with another aspect of the present invention, a method of forming a connection between a sleeve bearing member and a bearing housing of a connecting rod to prevent rotation of the sleeve bearing member relative to the bearing housing is taught. The sleeve bearing member includes first and second semi-cylindrical sleeve bearing members and the bearing housing includes a cap member and a body member. The cap member has a surface that is adapted for mating engagement with a like surface of the body member. The method includes the steps of inserting the first sleeve bearing member into the cap member and inserting the second sleeve bearing member into the body member, forcing the cap member toward the body member, and compressing at least one free end of the first sleeve bearing member and at least one free end of the second sleeve bearing member to thereby form at least one protrusion that extends from the bearing members and engages the bearing housing.
In further accordance with the present invention, the connection forming method includes forming at least one groove in the bearing housing to define a separation plane, and cracking the bearing housing along the separation plane to separate the cap member from the body member. The at least one groove receives the protrusion from the bearing members.
In accordance with other aspects of the present invention, a connecting rod assembly includes a small bearing end and a large bearing end having a pair of grooves cut therein to define a plane of separation about which the large bearing end is separated into a cap member and a body member. The large bearing end receives a bearing member that includes a first bearing member and a second bearing member. The first bearing member is secured to the cap member and the second bearing member is secured to the body member.
In further accordance with the present invention, the first and second bearing members have free ends that are forced into compressive engagement with one another. The compressive engagement deforms the free ends of the bearing members and creates protrusions that extend into the grooves. The protrusions serve as stops to prevent rotation of the first and second bearing members relative to the large bearing end.